There has been known a volume adjusting apparatus having a volume control circuit that controls the volume of an input audio signal, a user interface that is connected to the volume control circuit and capable of adjusting volume via the volume control circuit when operated by a user, an indicator that indicates an operating amount of a volume adjusting operation made to the user interface, a flash memory that stores an operation history and their audio output levels of volume adjusting operations as a volume indicated value/output level table, and a microcomputer that controls the volume control circuit. An example of such apparatus is disclosed in JP-A-2004-037823.
According to this volume adjusting apparatus, the microcomputer stores a history of 100 operations as a table showing relations between a volume indicated value and an output level in the flash memory, and calculates an average value of the history of 100 operations. The microcomputer controls the indicator to display the operation amount near the average value in more detail. Accordingly, the apparatus allows the user to set a desired volume more precisely.
However, there is a problem in the conventional volume adjusting apparatus that, in a case where the audio signal to be output is selected from a plurality of audio signals having different volume levels, the user is required to manually adjust the audio volume to the desired level each time the audio signal to be output is changed.